The fascist noose is tightening the world over thanks to proprietary big tech. We have to escape now while we can to open-source alternatives.
Currently the best (in my subjective opinion) self-hostable, encrypted and federated (like lemmy/piefed) alternative is Movim.
It offers 90% of the features of Discord, including group video calls, group texts, and even screensharing with audio (must use a Chromium based browser currently to share the audio). The only feature missing is discord-style rooms, which the dev is currently working on to release as fast as possible.
It doesn’t even require an email to create an account, and runs right in your browser, so it has an extremely low barrier to entry. Give it a try with a friend to see if it can meet your needs! :D
For a more complete guide to swapping proprietary apps for safe open-source ones, I suggest referring to this post: https://lemmy.cafe/post/18663514
That is what XMPP, which Movim uses, allows today. There are many XMPP clients available that can all federate and communicate with each other, and anyone can self-host an XMPP server. I’m only pointing people to Movim since it is the most full featured client and keeps things simple (which is very important when onboarding new less technical users).
If you mean that truly all services should federate, like even Matrix, Signal, etc… that’s technically possible if every company and developer agreed to a single standard, but practically impossible as they will never agree to that single standard for various reasons (NIH syndrome, lack of control to create profit or lock in users, ego, legitimate different use-cases, etc).